Script To Put Info For Randomly Selected Banners

I found the following script for random banner ads at [URL]. It is almost what I want, except it only appears to work once, and then no more. I suspect it has something to do with the "today" functions near the end, but being a complete novice, have no idea what to do to make it work every time I refresh.

Here's the script:
<SCRIPT>
<!-- written by The Omega
// [URL]
// the_omega@geocities.com
// You must leave these comments in to use the script
// (hey, I wrote it. Let me have a little credit!)

// put info for randomly selected banners here, as in the examples
gfx0="banner1.gif";
lnk0="page1.html";
alt0="Alt code 1";
txt0="Tagline 1";
gfx1="banner2.gif";

lnk1="page2.html";
alt1="Alt code 2";
txt1="Tagline 2";
gfx2="banner3.gif";
lnk2="page3.html";
alt2="Alt code 3";
txt2="Tagline 3";
len=3; // change to equal number of banners

today=new Date();
today=today.getTime()/10;
rnd=today%len;
document.writeln('<A HREF="'+eval("lnk"+rnd)+'"><IMG SRC="'+eval("gfx"+rnd)+'" ALT="'+eval("alt"+rnd)+'"><BR>'+eval("txt"+rnd)+'</A>');

//-->
</SCRIPT>
<p align="center"><font face="arial" size="-2">This free script provided by</font><br>
<font face="arial, helvetica" size="-2"><a href="[URL]">JavaScript
Kit</a></font></p>